1. Field of the Invention
This invention relates generally to radiant energy, and more particularly to a device for establishing desired pattern of radiation in space from a centralized source or; for concentrating at a point, radiating energy from a plurality of sources.
2. Description of the Prior Art
The present invention is normally used in conjunction with a cabinet mounted loudspeaker and an electrical frequency dividing network, in order to reproduce the entire audible sound spectrum. The human ear's perception of direction is most sensitive to high frequency sound. In a room the human ear normally has difficulty distinguishing the location or direction of low frequency sound. This is particularly true in the reverberant sound field where one would normally listen to a loudspeaker. This invention is intended to control the directionality of that part of the sound spectrum in which the ear is most sensitive.
The most pertinent prior art known to me is a so-called coherent-sound loudspeaker such as described in U.S. Pat. No. 3,424,873 issued Jan. 28, 1969 to Lincoln Walsh. That particular loudspeaker has evolved somewhat. In addition, Bruel and Kjaer manufactures the type 4241 isotropic sound source which employs twelve loudspeaker drivers mounted in a single enclosure. Both loudspeakers are suitable for creating a diffuse sound field suitable for performing indoor acoustical tests. Yet I understand that they remain fairly expensive, and there remains a need for an omni-directional loudspeaker assembly of less expensive construction capable of creating a diffuse sound field. The present invention is addressed to that need. A diffuse sound field is normally required to quantify the degree of sound absorption provided by the room boundaries and contents and quantify the degree of sound isolation between barriers separating architectural spaces.